Acting DEA Administrator Robert W. Patterson speaks at a press conference last month announcing indictments after the breakup of an alleged international fentanyl network with roots in China. He is flanked by Joanne Crampton of the Royal Canadian Mounted Police, left, and Deputy U.S. Attorney General Rod Rosenstein, right. (Photo: U.S. Department of Justice)

Last month two Chinese nationals were indicted for manufacturing fentanyl and distributing the powerful drug in the U.S., where it had led to at least a handful of documented deaths. One of the accused in particular was accused of closely monitoring American law enforcement, and carefully changing his chemical recipe of the drug to avoid prosecution under existing laws. The criminal complaint details dozens of unpronounceable compounds such as a-PBP, TH-PVP, 4-MEC and 2C-I, which were developed to mimic fentanyl while skirting the law.

Now the Drug Enforcement Agency is attempting to assist prosecutors nationwide in their push against the opioid epidemic, by scheduling all fentanyl-related substances through an order announced Thursday.

The idea is to give law enforcement a foothold against wily drug distributors by removing the “cumbersome evidentiary hurdles” prosecutors may face with new compounds.

“By scheduling all fentanyls, we empower our law enforcement officers and prosecutors to take swift and necessary action against those spreading these deadly poisons,” said Jefferson Sessions, the U.S. attorney general. “I also urge the many members of Congress who clearly share our concern and alarm over fentanyl’s role in our opioid overdose epidemic to do their part by permanently scheduling these lethal substances.”

The temporary scheduling of all the similar molecules will go into effect within 30 days of the coming DEA notice of intent. The measure will last two years, with the possibility of another year extension.

Currently, prosecutors would need to prove their case against manufacturers and distributors of new substances under the Analogue Act, a 1986 addition to the federal Controlled Substances Act written to combat “designer drugs.”

Such creative chemistry by the makers and dealers has previously been pursued by makers of synthetic cannabinoids and so-called “bath salts” stimulants. Scientists in laboratories domestic and foreign have played a cat-and-mouse game with authorities as they devise molecules intended to have the same effects as banned substances, while making them different enough to avoid the reach of the law.

The fatality stakes are higher with the synthetic opioids, however. Fentanyl and its analogues killed approximately 20,000 people in this country last year alone.

The new order will allow prosecutors to accelerate their cases involving the substances, said authorities.

“DEA is committed to using all of its tools to aggressively fight and address the opioid crisis and growing fentanyl problem plaguing the United States,” said Robert W. Patterson, the DEA’s acting administrator.

Fentanyl was first placed in strict international control in 1964, according to the United Nations Office on Drugs and Crime. As early as the 1970s, fentanyl appeared in black market drug networks, and became notorious for accidental overdoses. At least a dozen additional fentanyl analogues have appeared on the illegal markets over the last five years, according to the UNODC.